Seismic assessment of masonry arch bridges

In this paper, the seismic performance of existing masonry arch bridges is evaluated by using nonlinear static analysis, as suggested by several modern standards such as UNI ENV 1998-1 2003, OPCM 3274 2004, and FEMA 440 2005. The use of inelastic pushover analysis and response spectrum approaches becomes more difficult when structures other than the framed ones are investigated. This paper delves into the application of this methodology to masonry arch bridges by presenting two particular case studies. The need for experimental tests in order to calibrate the materials and the dynamic properties of the bridge is highlighted, in order to correctly model the most critical regions of the structure. The choice of the control node in the pushover analysis of masonry arch bridges and its influence on seismic safety evaluation is investigated. The ensuing discussion emphasizes important results, such as the unsuitability of the typical top node of the structure for describing the bridge seismic capacity. Finally, the seismic safety of the two bridges under consideration is verified by presenting an in-depth vulnerability analysis.